September

Daisy-like calendula provides easy color from late fall through spring in mild-winter climates, and are long lasting in a vase.

Choose classic orange and bright yellow, or opt for subtler shades of apricot, cream, and soft yellow. Branching plants are 1 to 2 feet high and 1 to 1½ feet wide and look great as masses of color or in a container.

Calendula plants take full sun and moderate water. They will tolerate many soils as long as they have good drainage. Remove the spent flowers to prolong bloom.

Photo by Flowerphotos / Getty Images

What to do in your Northern California garden in September

Julie Chai

Prepare

Before planting a new lawn or flower or vegetable beds, prepare the soil. Dig down 10 to 12 inches with a shovel or rotary tiller, then till in a 4- to 6-inch layer of compost or other organic matter. You can also add a complete fertilizer to lawn areas.

Plant

September marks the beginning of fall planting season -- the ideal time to get many plants into the ground. Most nurseries are well stocked now with trees, shrubs, vines, and groundcovers.

Give cool-season annuals a strong start by planting after midmonth in cooler areas and at the end of the month in warm inland locations (Sunset climate zones 7-9, 14-17). Keep the soil moist while plants develop and, if weather is hot, temporarily shade new seedlings. Set out calendula, forget-me-nots, Iceland and Shirley poppies, ornamental cabbage and kale, pansies, primrose, stock, sweet peas, and violas. In coastal areas, try cineraria, nemesia, and schizanthus.

Shop soon for the best selection of healthy bulbs; choose firm ones without soft or moldy spots. Plant anemones, crocus, daffodils, Dutch iris, freesias, homeria, hyacinths, ixia, leucojum, lycoris, oxalis, Peruvian scilla, ranunculus, sparaxis, tritonia, tulips, and watsonia. (Some, such as freesias, homeria, and watsonia, are not hardy in zones 1 and 2.) In mild climates, chill crocus, hyacinths, and tulips in the refrigerator for about six weeks before planting, keeping them away from fruits and veggies, which can thwart bulb development.

Cool-season greens like arugula, chard, kale, lettuce, and mustard are some of the easiest vegetables to grow from seed and have much better flavor than store-bought types. For a wide selection of varieties, try a seed source such as Ornamental Edibles.

If perennials like agapanthus, candytuft, coreopsis, daylilies, and penstemon are overgrown or not flowering well, it's time to dig and divide them. (Zones 1 and 2: Do this early in the month.) You can also divide these plants to increase their numbers in your garden. Use a spading fork or shovel to lift clumps, then cut the clumps into sections with a spade, shovel, sharp knife, or pruning shears. Replant sections in well-amended soil and keep moist while new roots develop.

Harvest

Continue picking your summer tomatoes. Dig or pull up any plants that have finished producing or have succumbed to disease; add only undiseased plants to your compost pile.